See many MBBS professionals are working as IAS officers. The main advantage in this are as an IAS you will be more sensitive to the Hospital Facilties, you will be able to judge about the disputes that may occur in Hospital structures more than any other field graduates. Also as you are a doctor and as you have a lot of interactions with the patients, so your people skills will be better and will have kindness in it, which comes inbuild a quality. So this are some of the advantages which you will get.  Also when you are posted to as a Secretary then you will have better chances to go for the Health Departments.

And yeah! If you are a registered doctor and if you want to work as a Doctor for Charity then you can obviously do that without any doubt.

For preparation tips IAS, visit the link below:

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

I hope this answer helps. All the very best for your future endeavors!